As shown by FIG. 9, standpipe 224 has a floor 264 which includes sloped or ramped portions 265 that slope or ramp towards slots 226. As a result, ramped portions 265 form an angle with the vertical walls 265 of standpipe 224 that is greater than 90 degrees and also forms an angle with a top of slots 226 that is greater than 90 degrees. Such larger transition angles reduce the likelihood of air bubbles becoming trapped or lodged along floor 264 and proximate to slots 226 where they may at least partially occlude flow of printing fluid. According one embodiment, floor 264 extends at an angle of at least about 160 degrees and nominally about 150 degrees with respect to vertical walls 265 and forms an angle of at least about 130 degrees and nominally about 120 degrees with respect to a top of slots 226. In other embodiments, floor 264 may extend at other angles or may alternatively extend perpendicular to walls 265.